How to get the best polished concrete Concrete Polishing Guide 2015.pdfHow to get the best polished...
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How to get the best polished concrete floor
The complete step-by-step floor polishing guide to achieve a full gloss 3000# finish
Modern, durable and stylish, polished concrete floors are also one of the most eco-friendly flooring options available today. When correctly done, polished concrete floors can enhance the value of both domestic and commercial buildings.
To achieve the best polished concrete floor, your tools, tips and techniques need to be first class. The All Preparation Equipment team have put together this step-by-step guide to help you get the best result from your concrete floor polishing project.
www.AllPrep.com.auPH 1800 422 992
Wear the right PPE (Personal Protective Equipment) at all times whilst working. Breathing in concrete dust is harmful. Use a dust mask, ear protection, foot, hand and eye protection while grinding.
Take care to keep the grinder flat. If you hold it on an edge youll create gouges in the concrete surface which will be very difficult to remove.
Be careful not to over-grind the edge as it is often easier to grind than the centre of the slab
If the concrete is a new or freshly poured slab, you may risk pulling out the aggregate prior to proper curing.
Make sure you let the grinder do the work, rather than your body weight. Thats because pushing too hard can create a 3-4mm deep gutter around the edge of the grinding area which will be a big problem to contend with later.
APEs TOP TIPS
STEP 1GRIND THE EDGES
Connect either a small hand-held variable speed angle grinder or the Schwamborn DSM250 walk-behind edge grinder to a compatible dust extraction system. Then, carefully grind around the perimeter of the concrete area to be polished. Its a good idea to use a medium bond 30/40# diamond on your grinder at this stage.
The number one thing you must do before attempting a full 3000# polish is to choose a quality built planetary concrete grinder. These machines will flatten, hone and level the concrete floor, and give you a much higher gloss finish thanks to their planetary grinding action.
With a reputation built on over 80 years of designing and manufacturing grinders (and from feedback from our happy customers!) the king of planetary concrete grinders is undoubtedly Schwamborn. Made in Germany, Schwamborn concrete grinders feature the knock-on diamond grinding shoe system, variable speeds, and water tanks all of which give you the edge before you even start the job.
Before you start grinding, check the surface carefully for any defects, including cracks, honeycombing, or pinholes. Any minor defects will be taken care of curing the grouting process; but if you spot any significant damage, youll need to rectify it with high quality repair mortar before going any further.
Before you begin
STEP 2BEGIN GRINDING EAST TO WEST
Using a walk-behind Schwamborn planetary concrete grinder with medium bond 30/40# diamond tools, start grinding the main surface area. Start at one side and grind east to west across the entire floor, overlapping each grinding pass by about 1.4 of the machine width. Make sure you grind as close as possible to the previously ground edge areas, overlapping the grinding marks with the walk-behind grinder.
Set your variable speed grinder at about half speed for this stage.
STEP 3CONTINUE GRINDING NORTH TO SOUTH
Once youve completed the east to west grinding, its time to change directions and move to a north to south pattern, again taking care to slightly overlap with each pass and grind right up to the hand-ground edge areas.
Repeat this grinding process until youve exposed the desired amount of concrete aggregate. Its important to note that this stage is where the finished look is determined. The next steps wont remove as much material or expose more aggregate so if you decide youd like to see more aggregate in the finished polished floor, go back and repeat steps 2 and 3 until you get the look you want.
Use a slight swinging motion as you move forward with the walk-behind concrete grinder, and grind as close as you can to the hand-ground edges to blend these areas together.
Modify your pace depending on the concrete surface youre dealing with. Youll know your pace is right if your grinder leaves a solid grind, without obvious swirl patterns in the concrete. If swirls are present, its a sure sign you need to slow down.
Switch to a softer diamond bond of the same grit if you notice youre suddenly not grinding as effectively as you were. This can happen as you uncover harder concrete once the softer top layer has been removed.
Vacuum up residual concrete dust if it starts to cause problems. Youre removing a lot of concrete and it has to go somewhere. Take a break from grinding and tidy up the area if necessary. Often a squeegee is used to push excess dust into a pile for collection.
APEs TOP TIPS
STEP 4CHECK YOUR AGGREGATE EXPOSURE
Once you feel youve exposed the right amount of aggregate, switch off your grinder and do a thorough vacuum of the floor area. This will let you get a clear look at the exposed aggregate as well as any imperfections in the concrete floor.
If youre satisfied with the aggregate exposure, move on to step 5. If you want to expose more aggregate, go back and repeat steps 2 and 3.
STEP 5REMOVE SCRATCH MARKS FROM THE FLOOR EDGES
Going back to your hand-held grinder or Schwamborn DSM250 edge grinder, replace the 30/40# diamond disc with a medium bond 60/80# diamond disc. Re-grind the perimeter per step 1 above.
Take care to grind as close as you can to the edges of the concrete floor. After this stage, the initial 30/40# scratches should be removed and only very fine scratches should be visible in the edge areas.
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STEP 6REMOVE SCRATCH MARKS FROM THE MAIN FLOOR AREA
Just as youve done with the edge areas, its now time to replace the tooling on the walk-behind floor grinder with 60/80# diamond tooling. Use the same technique described in steps 2 and 3 above, grind east to west and then north to south.
STEP 7FURTHER GRINDING AND CHECKING FOR DEFECTS
With the walk-behind grinder, change to 120# diamond tooling and repeat steps 2 and 3 once more. Then, carry out a detailed vacuum to remove all dust and get a clear view of your work so far.
After youve completed this stages east to west and north to south passes, the initial scratch marks from the 30/40# should be gone. If you can still see significant scratches, repeat step 6 until they are thoroughly removed.
Its a good idea to vacuum the area at this point to get a clear look and check for scratches.
Take care when removing diamond tooling as they may be very hot!
If you do notice that extensive repairs are needed, make sure you stick to the product instructions for your chosen repair material. You may wish to perform the grouting step first, as this is often enough to fill up the small divots, pinholes or cracks (known as defects) in the concrete.
APEs TOP TIPS
APEs TOP TIP
STEP 8GROUTING THE FLOOR
Once any necessary repairs have been completed, and the repair material has thoroughly cured, its time to begin grouting the concrete floor. Liquid grout can be an effective way to fill any defects where small pieces of aggregate have been pulled out during the grinding process.
Make sure you only do small areas at a time. Its important to work out how many m2
you have the manpower to grout at a time, before it sets off on the surface.
With a small portable hand pump, spray about a 5-10m2 area with the liquid grout. You may also use a microfiber mop or soft broom for the application. Next, using the medium bond 120# with your walk-behind grinder, grind over the sprayed area. Keep the variable speed control at about halfway, but reduce speed if the surface has extensive defects.
Depending on the type of grout youre using, you may wish to hydrate the floor first to prevent the grout soaking in below the surface. Often theres no need to use the vacuum during this stage, as you want the small amount of dust created to mix with the liquid grout, to form a paste which will fill small defects. Grind over the concrete floor until this paste turns back to concrete dust.
Make sure you only work on about 5-10m2 at a time. Trying to work on a larger area will result in the liquid grout hardening which will mean re-doing your careful grinding work! Larger grinders will cover larger areas so assess your ability first!
You may find you need extra applications of grout to fully plug all defects. If you find that defects are still visible after 3 grout applications, its time to use a repair mortar instead.
Thoroughly wash your equipment before the grout sets hard as a paste.
After grouting, give the floor area a light vacuum to remove any excess grout or concrete dust.
APEs TOP TIPS
STEP 9APPLY CONCRETE DENSIFIER
The next stage is applying a chemical treatment called densifier to the concrete floor area, to harden the newly exposed surface. Densifiers penetrate into the substrate of the concrete floor to dramatically harden the top 2-5mm.
Its a great idea to discuss the best type of densifier for your specific project with the polishing team at All Preparation Equipment.
Spray the entire floor area with densifier using a knapsack sprayer, then leave it to cure for about 6-12 hours. Once fully cured, use the walk-behind grinder with 120# diamonds to grind away the skin of excess densifier that forms. One pass is generally sufficient.
Densifier curing time will vary depending on the weather conditions where